１００ｋｇ／ｃｍ?Q２?R級舶用ボイラとう載の出光丸におけるボイラ蒸発管内面スケールの生成について Ｉ

Abstract

Careful attentions have been paid to boiler and feed water treatment in case of operating the pressure of 100 kg/cm2 class marine boilers installed on the tanker“Idemitsu Maru”, for the purpose of minimizing damage to the inner surface of boiler tubes due to an obstruction of heat transfer by scaling and alkali corrosion.Some investigations concerning scale formation on the inner surface of boiler tubes have been continued to cross check the above mentioned water treatment. The results are as follows.(1) After 8 years operation, the max. inner scale mass is only about 50 mg/cm2and the location is the fire-side of rear water wall panel, 3300-3400 mm hight from furnace floor level. This boiler and feed water treatment will be certainly satisfactory for the protection from obstruction of heat transfer by scaling.(2) The alkali corrosion on the inner surface of boiler tubes after descaling is not observed at all. This boiler water treatment will be certainly satisfactory for the protection of alkali corrosion.(3) The formation rate of inner scale on the fire-side is approximately two times compared with anti-fire side of rear water wall panel for both reheat and straight boilers.(4) The formation rate of inner total scale and Fe3O4of its main component increases exponentially, but ZnO and Cu component in the scale picked up from feed water system and PO4component deposited from boiler water increase linearly. However, the formation rate of CaO, MgO and SiO2component increases little anti-exponentially. This increasing rate may depend upon slightly delayed regeneration of ion exchange resin for make up water.